After being placed near the station, the artifact begins to influence the dreams of many inhabitants of Babylon 5, and eventually controls many of them during their waking hours as well. These thralls, led by Deuce, first demand that the excavation be accelerated and then become increasingly violent towards the rest of the Babylon 5 population.

Eventually it is revealed by Lyta Alexander that the artifact is a Jumpgate built by the Vorlons a million years ago with a purpose that cannot be expressed in human language except as an attempt to make contact with the gods. In reality, Thirdspace is inhabited by a violent race that posed a threat even to the Vorlons, and the ensuing battle ended with a group of Vorlons controlled by the Thirdspace entities capturing the artifact and jettisoning it into hyperspace.

When the device is finally activated, the Thirdspace aliens stream out and begin an assault on Babylon 5; the violent behavior of the individuals under the artifact's control is intended to disrupt the station's attempt to defend itself. The struggle is ended when John Sheridan enters the artifact and detonates a nuclear bomb.

The movie is somewhat difficult to place, as it does not actually slot neatly into any timeframe between episodes, especially given the significant expenditure of resources the incident depicted represents. The best fit for it is generally agreed to be before or during the Season 4 episode "Atonement". Placing it here makes the only truly glaring continuity error the premature appearance of Zack's new uniform, though other questions are raised about later episodes, such as damage to the station and the lack of references to what would have been a major incident at B5 and how it would have affected larger events.

"It was the middle of the Earth year 2261. The year between wars and the beginning of a new age."
"The Shadow War was over, but there was still a darkness waiting for us at home."
"President Santiago had been assassinated, and his successor President Clark was turning Earth into a prison camp."
"We'd broken away from Earth, and in retaliation, they quarantined us...trying to strangle our supply lines."
"We were desperate and we couldn't afford to lose even a single supply ship."
"In the midst of all of this, we made contact with Thirdspace...and we almost didn't survive it."
"I only hope we never come across it again...because next time, no one's going to survive it."